JPH0644621Y2 - Robot hand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a robot hand, and more specifically, to a robot hand capable of detecting whether or not a work of an appropriate size is detected.

<Problems to be Solved by Conventional Techniques and Inventions> Conventionally, industrial robots have been equipped with a hand for gripping a work, a tool, etc. By operating a robot arm, the hand can be moved to a desired position. In the moved state, the work, tool, etc. are gripped so that the necessary work can be performed.

However, the hand is generally attached to the tip of the robot arm so that it can be opened and closed, and the hand is opened and closed when the robot arm moves to a predetermined position taught in advance. It is not possible to detect whether or not a work piece of an appropriate size is gripped.
That is, since the completion of gripping the work is generally detected based on an increase in the amount of electricity supplied to the motor for moving the grip claw, it can be determined whether or not the work is gripped. However, there is a problem that the size cannot be detected.

In order to solve such a problem, a proximity switch is provided at a predetermined position of the grip claw support, and whether or not the work size is appropriate based on the state of the proximity switch when it is determined that the grip is performed. It is possible to judge whether or not. However, if such a configuration is adopted, the work size that can be discriminated is determined by the attachment position of the proximity switch, and the versatility of the robot hand is greatly impaired. Although it is possible to provide a plurality of proximity switches in consideration of such a point, it is not possible to mount a large number of proximity switches at extremely small intervals, so that not only can versatility not be improved. However, there is a problem that the number of signal lines increases and it is impossible to identify a work whose size difference is not so large.

In addition, a dog that changes the detected area is attached to the moving part of the robot hand, a sensor is attached to the fixed part of the robot hand, and a device that detects the size of the gripped article based on the dog detection signal from the sensor (actual opening (See Sho 59-15905 gazette), to measure the material diameter at the same time as the centering of the round material,
A device that employs a rack and pinion mechanism that is interlocked with the movement of one of the pawls and that is provided with a potentiometer that operates by a pinion (see Japanese Patent Laid-Open No. 58-56792), a gripping device that is driven by compressed air. , A gripping device that can obtain an arbitrary opening by detecting the opening with a pulse encoder (see Japanese Utility Model Laid-Open No. 63-21584), and a dog having a plurality of slits on one gripping arm of a robot hand. A robot hand device (see Japanese Patent Laid-Open No. 63-99190) that attaches a sensor to the other gripping arm of the robot hand, counts the number of times the slit passes through the sensor, and detects the stroke amount of the gripping arm Has been done.

However, any of the devices can only detect the size of the work in the gripping direction, and it is absolutely impossible to detect the size of the work in the direction orthogonal to the gripping direction or the presence or absence of the work. is there.
Therefore, for example, even if the workpieces have the same outer diameter and different heights, it is completely impossible to detect whether or not they are proper workpieces, and the types of applicable workpieces are limited. It will be.

<Purpose of Invention> This invention was made in view of the above problems.
An object of the present invention is to provide a robot hand that can easily detect not only the size of a work in the gripping direction but also the size of the work in the direction orthogonal to the gripping direction and the presence or absence of the work.

<Means for Solving the Problems> In order to achieve the above-mentioned object, a robot hand of the present invention has a work gripping part connected to a hand main body via a floating mechanism so that the work gripping part can be contacted and separated.
A member for detecting the contact / separation state is provided for one of the hand main body and the work gripping portion, and a plurality of detecting means for detecting the members arranged in the moving direction of the work gripping portion is provided for the other. A potentiometer that is operated by one of the gripping claws that come into contact with and separate from each other is provided at a predetermined position of the work gripping portion.

In the robot hand of the second invention, the work gripping portion is connected to the hand main body via a floating mechanism so that the work gripping portion can be brought into contact with and separated from the hand main body, and the hand gripping portion is used to detect a contact / separation state with respect to one of the hand main body and the work gripping portion. A plurality of detecting means for detecting the above-mentioned members arranged in the moving direction of the work gripping part with respect to the other, respectively, and gripping claws that come into contact with and separate from each other at predetermined positions of the work gripping part. A digital scale is provided which is operated by one of the two.

<Operation> In the robot hand having the above configuration, since the potentiometer that is operated by one of the gripping claws that come in contact with and separate from each other is provided, the distance between the gripping claws is determined based on the electric signal output from the potentiometer. That is, the work size can be identified. Since the electric signal output from the potentiometer changes continuously, it is possible to determine whether or not the work has an arbitrary size by setting an arbitrary threshold, for example.
In addition, the work gripping part connected to the hand body via the floating mechanism approaches the hand body according to an external force,
Since the number of detecting means for detecting the contact / separation state detecting member changes according to the degree of approach, it is possible to detect the size of the work in the direction orthogonal to the gripping direction of the gripping claws and the presence or absence of the work. it can. Therefore, it is possible to identify works having the same size in the gripping direction and different sizes in the direction orthogonal to the gripping direction. Also,
The presence or absence of a work can also be detected.

In the case of a robot hand having another configuration, since a digital scale that is operated by one of the gripping claws that come in contact with and separate from each other is provided, the distance between the gripping claws based on the digital signal output from the digital scale, That is, the work size can be identified. Since the electric signal output from the digital scale continuously changes, for example, by setting an arbitrary threshold value, it is possible to determine whether or not the work has an arbitrary size. Further, when supplying the above signals to the processing system that performs digital processing, an A / D converter is not required, and the configuration can be simplified as a whole. Further, the work gripping part connected to the hand main body through the floating mechanism approaches the hand main body in response to an external force, and the number of detecting means detecting the member for detecting the contact / separation state in accordance with the degree of the approach. Changes, it is possible to detect the size of the work and the presence / absence of the work in the direction orthogonal to the gripping direction of the grip claws. Therefore, it is possible to identify works having the same size in the gripping direction and different sizes in the direction orthogonal to the gripping direction. Further, the presence or absence of the work can be detected.

<Example> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating an example.

FIG. 7 is a schematic view showing an example of an industrial robot equipped with the robot hand according to the present invention. The robot hand (7) is attached to the arm tip of the SCARA robot (6) for assembly.
And a switching valve (8) for supplying a pressure fluid for the opening / closing operation to the robot hand. A robot controller (9) is provided that takes in signals indicating the pressing state and the open / closed state of the robot hand (7) and supplies necessary control signals to the switching valve (8). It goes without saying that the robot controller (9) outputs a control signal for operating the robot arm. still,
(91) is an A / D converter for digitizing an output signal from a potentiometer (51) described later.

Therefore, by operating the robot pot until the robot hand (7) is pressed against the work, tool, etc., and opening and closing the robot hand (7) until it is opened and closed, the work, tool, etc. Etc. can be grasped and released.

FIG. 6 is a schematic front view showing an embodiment of the robot hand of the present invention. A hand body (1) attached to a robot arm (not shown) and a work holding part (2) for holding a work, a tool and the like. And a floating mechanism (3) for connecting the work gripping part (2) to the hand body (1) so that the work gripping part (2) can be contacted and separated, and urging the work gripping part (2) in a direction away from the hand body (1). It has a state detecting section (4) that is mounted on the workpiece and a gripping position detecting section (5) that is mounted on the workpiece gripping section (2).

FIG. 1A is a front view showing a gripping position detecting section, and FIG. 1B is a side view showing the work gripping section (2) with a potentiometer (5).
1) is attached, and the potentiometer (5
The movable part (52) of 1) is connected.

Therefore, if a predetermined voltage is applied between both fixed terminals of the potentiometer (51), the voltage corresponding to the opening degree of the grip claws (21) (22) is output from one fixed terminal and the movable terminal. .

FIG. 2 is a block diagram showing an electrical configuration for detecting the work size. The output voltage from the movable terminal of the potentiometer (51) is digitized by the A / D converter (91), and the digitized voltage signal is shown. Is supplied to the comparators (53) (54) to which a predetermined reference voltage has been set in advance, and the output signals from both comparison devices (53) (54) are encoder (55).
Is being supplied to.

Therefore, the encoder (55) outputs a signal indicating whether it is within the range of the work size determined based on the reference voltage of both comparators (53) and (54), or is larger or smaller than this range, and this signal is output to this signal. Based on this, the required robot control can be performed by the robot controller (9). It is preferable that the reference voltage of each of the comparators (53) (54) can be easily set or changed by a robot teaching operation or the like. The same operation can be performed by software without using the comparators (53) (54).

FIG. 4A is a front view showing in detail the floating mechanism and the state detection unit, and FIG. 4B is a side view showing the hand body (1) and the work gripping unit (2) contacting and separating by the guide shaft (31). Coil springs (32) as well as possible connected
Is urged to slide so that they are separated from each other. Then, at a predetermined position of the mounting plate (41) protruding from the predetermined position of the work gripping part (2) toward the hand body (1),
Two proximity switches (4
2) (43) is attached. Further, a projection plate (44) for driving the proximity switch is attached so as to project from a predetermined position of the hand body (1) toward the work gripping portion (2).

Therefore, when no external force is applied to the work gripping part (2), as shown in FIG. 5A, neither of the proximity switches (42) (43) directly faces the projecting plate (44). When an external force acts on the work gripping part (2) to approach the hand body (1) to a predetermined position, only one of the proximity switches (42) has a protruding plate (44) as shown in FIG. 5B. ),
When the work gripping part (2) further approaches the hand body (1), as shown in FIG.
2) (43) faces the protruding plate (44).

The operation of the industrial robot having the above configuration is as follows.

First, the operation of the robot arm necessary for gripping a work, a tool, etc., the pressing state of the work gripping part (2), the position of the grip claws (21) (22) necessary for gripping, teaching, pendant, etc. To teach in advance.

After that, by performing a robot operation based on the teaching data, it is possible to grasp a work, a tool, etc. arranged at a predetermined position. After performing necessary processing based on the gripped work / tool, etc., the gripped state is released and the arm is moved to the standby position to prepare for the next series of operations.

The above explanation is the operation when the desired work, tool, etc. are set accurately in the predetermined position.When there is no work, tool, etc., when different kinds of work, tools, etc. are set, etc. Can detect an abnormal condition as follows. That is, if there is no work, tool, etc., no external force acts even if the robot hand (7) is moved to a pre-instructed position, so that the work gripping part (2) moves from the hand main body (1). Remains farthest away. Therefore, as shown in FIG. 5A, each of the proximity switches (42) (43) has a protruding plate (44).
Since it does not directly face with and remains OFF, both proximity switches (4
2) Based on the OFF signal output from (43), it can be detected that there is no work or tool. Further, when a work, tool, etc. higher than the normal height is set, the work gripping part (2) is held by the hand body until the robot hand (7) is moved to the pre-instructed position. Remarkably approaches (1). Therefore, as shown in FIG. 5C, both proximity switches (42) (4
Since 3) faces the protruding plate (44) and turns on,
It is possible to detect that the wrong work, tool or the like is set based on the ON signals output from the both proximity switches (42) (43). In the latter case, it is possible to prevent the abnormal reaction force from acting on the robot hand (7) by stopping the robot operation based on the detection signal.
It is possible to prevent damage to tools and the like. The states shown in FIGS. 5A and 5C occur not only when the wrong work or tool is set, but also when the robot is moved toward a different position due to a teaching error.

In the above, only the case of gripping the work, tool, etc. is explained. However, even when the work, tool, etc. are released, the OFF signal or ON from both proximity switches (42) (43)
By outputting the signal, it is possible to detect that the work on the other side does not exist, that there is a mounting error due to twisting, or the like.

In addition, when a work, tool, etc. with a proper height is set at the proper position, the work, tool, etc. are gripped by bringing the gripping claws (21, 22) close to each other. Since the signals corresponding to the openings of (21) and (22) are output from the potentiometer (51), the planar size of the work, tool, etc. can be identified based on the output signal. That is, the output signal is the A / D converter (9
Since it is digitized by 1) and supplied to both comparators (53) and (54), for example, when a work of an appropriate size is gripped as shown in FIG. ) (54) outputs high-level and low-level signals, and when a small workpiece is gripped as shown in 3A, both comparators (53) (54) output low-level signals. When a large size work is gripped as shown in FIG. 3C, a high level signal is output from both comparators (53) and (54). Then, based on the output signals from both comparators (53) (54), the encoder (5
A code signal indicating the work size is output from 5).
As a result, it is possible to reliably determine the suitability even for works, tools, etc. having different plane sizes only.

Also, the range of the work size to be determined as the proper size can be finely set within the range determined based on the resolution of the A / D converter (91).

As is clear from the above description, the main body of the potentiometer (51) is attached to one grip claw, and the movable part (52) of the potentiometer (51) is attached to the work grip (2) main body.
The same operation can be performed by connecting the.

<Embodiment 2> FIG. 8 is a front view of an essential part showing another embodiment. The only difference from the embodiment of FIG. 1 is that a digital scale (56) is provided in place of the potentiometer (51). Is.

Therefore, in the case of this embodiment, the grip claws (21) (2
Since the digital signal corresponding to the opening of 2) is output from the digital scale (56), the A / D converter (9
It is possible to achieve the same operation as that of the above embodiment by omitting 1).

In any of the above embodiments, the work holding part (2)
Proximity switch for detecting the relative position of (42) (43)
Alternatively, a potentiometer (51) can be used, and in this case, the relative position to be detected can be easily changed. The grip claws (21) (22) are
It is preferable that not only the outer shape can be gripped but also the inner diameter can be gripped, and a wide range of works, tools and the like can be dealt with.

<Specific Example> FIG. 9 is a schematic perspective view showing a robot hand capable of gripping an electric screwdriver for screw tightening. The point different from the above embodiment is the middle of the grip claws (21) (22). It is only that the gripping claws (23) (24) dedicated to the electric driver are integrally projected from the section.

FIG. 10 is a schematic vertical sectional view showing the structure of the electric screwdriver (10), and FIG. 11 is a schematic perspective view showing the state of being held by a stand. The holder for gripping the electric screwdriver (10) at a predetermined position. (11) is integrally provided, and a replaceable screw tightening bit (12) is provided inside. A bolt holding portion (13) for accommodating the bolt supplied from the feeder (14) and controlling the posture so that the screw can be tightened is provided at the tip portion. In addition, (1
5) is a stand for holding the electric screwdriver (10) when it is not needed.

Therefore, in this specific example, the electric driver (10) can be taken out from the stand (15) by causing the gripping claws (23) and (24) to approach each other after the robot operation is performed to a predetermined position. . In this case, whether or not the electric driver (10) is appropriate can be determined based on the opening degrees of the grip claws (23) (24). Then
The screw operation can be performed by causing the robot operation so that the electric screwdriver (10) directly faces the screw tightening location and driving the electric screwdriver (10).

If the work to be screwed is not set,
Even if the robot hand (7) moves to a predetermined position, the external force does not act on the work gripping portion (2), so that it is possible to detect the absence of the work as in the above-described embodiment. On the contrary, when a work higher than the regular work is set, or when the set state of the work is improper, the work gripping part (2) is moved before the robot hand (7) is moved to a predetermined position. Is extremely close to the hand body (1), it is possible to detect a work setting error as in the above embodiment.

Further, in this specific example, if the electric screwdriver (10) is simply used for temporary tightening, it can be sufficiently dealt with by the SCARA robot for normal assembly work, and compared with the conventional screw tightening robot. A remarkably inexpensive screw tightening robot can be provided. Further, in this specific example, the state in which the electric driver (10) is held and the state in which another work, tool, or the like is held can be selected, so that versatility can be significantly improved.

The present invention is not limited to the above-described embodiment, and for example, the number of proximity switches can be reduced or increased, and the proximity switches (42) (4
It is possible to use a photoelectric switch or the like in place of 3), and it is possible to apply not only to the outer diameter grip of the work but also to the inner diameter grip, and within the range not changing the gist of the present invention. It is possible to change the design of.

<Effect of Device> As described above, the first device can extract the opening degree of the gripping claw as an analog electric signal, and can finely detect the size of the work or the like based on this signal, and further, the hand With the part moved to the specified position,
It is possible to detect the presence / absence of a work and the size of the work in the direction orthogonal to the gripping direction based on the number of detecting means detecting the contact / separation state detecting member.

The second invention is to extract the opening degree of the gripping claw as a digital electric signal, and to detect the size of the work or the like finely based on this signal, and to incorporate the detection signal into the digital signal processing unit. At A / D
A converter is not required, the configuration can be simplified, and moreover, in the state where the hand part is moved to a predetermined position, the number of detecting means detecting the contact / separation state detecting member The practicable effect peculiar to the presence or absence and the size of the work in the direction orthogonal to the gripping direction can be detected.

[Brief description of drawings]

1A is a front view showing a gripping position detection unit, FIG. 1B is a side view, FIG. 2 is a diagram showing an electrical configuration for detecting a work size, and FIG. 3 is a schematic view of a work size detection operation. 4A is a front view showing the floating mechanism and the state detection unit in detail, FIG. 4B is a side view, FIG. 5 is a view for explaining the relationship between the proximity switch and the projecting plate, and FIG. 6 is FIG. 7 is a schematic front view showing an embodiment of a robot hand of the present invention, FIG. 7 is a schematic view showing an example of an industrial robot equipped with the robot hand of the present invention, and FIG. Front view, FIG. 9 is a schematic perspective view showing a robot hand adapted to hold an electric screwdriver for screw tightening, FIG. 10 is a schematic vertical sectional view showing the structure of the electric screwdriver, and FIG. 11 is a stand. FIG. 3 is a schematic perspective view showing a state of being held by the. (21) (22)… Grip claw, (51)… Potentiometer, (56)… Digital scale

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-56792 (JP, A) JP-A-63-99190 (JP, A) JP-A-51-55076 (JP, A) Actual development Sho-59- 15905 (JP, U) Actually opened 63-21584 (JP, U)

Claims (2)

[Scope of utility model registration request] 1. A hand gripping part (2) is connected to a hand body (1) via a floating mechanism (3) so as to be able to come into contact with and separate from the hand body (1), and the hand body (1) and the work gripping part (2). Member for detecting contact / separation state of one side (44)
However, a plurality of detecting means (42) for detecting the member (44) arranged in the moving direction of the workpiece gripping portion (2) with respect to the other
(43) are provided respectively, and the gripping claws (21) (22) that come into contact with and separate from each other at a predetermined position of the work gripping part (2).
A robot hand characterized in that a potentiometer (51) that is operated by one of the two is provided. 2. A work gripping part (2) is connected to a hand body (1) via a floating mechanism (3) so that the work gripping part (2) can be brought into and out of contact with the hand body (1) and the work gripping part (2). Member for detecting contact / separation state of one side (44)
However, the detection means (42) for detecting the plurality of members (44) arranged in the moving direction of the workpiece gripping portion (2) with respect to the other
(43) are provided respectively, and the gripping claws (21) (22) that come into contact with and separate from each other at a predetermined position of the work gripping part (2).
Digital scale operated by one side (56)
A robot hand, characterized by being provided with.